JP2007267032A - Imaging apparatus and method for manufacturing imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform position adjustment including distortion adjustment for CCDs, to secure installation precision of each CCD and also to secure reliability for installation of the CCDs in an imaging apparatus comprising color separation prisms and the CCDs. <P>SOLUTION: The imaging apparatus has the color separation prisms 1, 2, 3 which decompose incident light into red band light, green band light and blue band and the CCDs 6, 7, 8 which receive each color band light emitted from the color separation prisms 1, 2, 3, respectively, either of the CCD 8 for red light or the CCD 7 for blue right is coupled to the corresponding emission surfaces of the color separation prisms 1, 2, 3 without interposing an air layer and two other CCDs are held to the corresponding emission surfaces via the air layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an imaging apparatus used in a video camera and various camera lenses, and a method for manufacturing such an imaging apparatus.

  In video cameras and various camera lenses, an imaging device that separates and captures incident light into light of different wavelengths, for example, the three primary colors of light (R (red), G (green), and B (blue)) is used. Has been. Such an image pickup apparatus is composed of a color separation prism and a solid-state image pickup device (CCD, MOS, etc.) that receives R, G, and B primary color band lights separated by the color separation prism.

  The color separation prism includes a plurality of prism members and a color separation film formed on at least one of the prism members, and the plurality of prism members are configured by bonding their optical surfaces to each other. .

  A video camera equipped with such an imaging device is called a so-called “3CCD camera system” or “3MOS camera system”. The “3CCD camera system” can capture images with better image quality in terms of color reproducibility and the like than a video camera that performs color separation using a color filter or the like without using a color separation prism and receives light with a single image sensor. . For this reason, the “3CCD camera system” has been conventionally used as a commercial video camera. However, in recent years, it has also been used as a consumer video camera, and there is an increasing demand for reduction in mass production and miniaturization. .

  The color separation prism constituting the image pickup apparatus as described above is composed of three prism members (G prism, B prism and R prism). As such a color separation prism, Patent Document 1 describes a color separation prism (gapless prism) having a simple configuration in which all the prisms are closely bonded without providing an air gap.

  As shown in FIG. 3, the color separation prism includes a G prism 101 to which incident light A from the imaging lens is incident, a B prism 102 that is closely bonded to the G prism 101, and a close bond to the B prism 102. The R prism 103 is configured. A first dichroic film 104, which is a color separation film that reflects green band light, is formed between the G prism 101 and the B prism 102, and blue band light is formed between the B prism 102 and the R prism 103. A second dichroic film 105 that is a color separation film that reflects light is formed. The G prism 101 is provided with a light shielding groove for stopping ghost light.

  In this imaging apparatus, incident light A from an imaging lens (not shown) to the color separation prism reaches the first dichroic film 104 via the G prism 101, and only the green band light is reflected by the first dichroic film 104. Then, color separation is performed by transmitting other color components. The green band light reflected by the first dichroic film 104 is totally reflected by the inner surface of the G prism 101, then exits from the exit surface of the G prism 101, and is received by the green band light imaging device 106. .

  The light transmitted through the first dichroic film 104 passes through the B prism 102 and reaches the second dichroic film 105, where only the blue band light is reflected and other color components are transmitted. Color separation is performed. The blue band light reflected by the second dichroic film 105 is emitted from the emission surface of the B prism 102 and received by the blue light imaging element 107. A B trimming filter 102 a is tightly bonded to the emission surface of the B prism 102.

  The light (red band light) that has passed through the second dichroic film 105 passes through the R prism 103, exits from the exit surface of the R prism 103, and is received by the red light imaging element 108.

  In this manner, in this imaging apparatus, the G prism 101 guides only the green band light to the green light imaging element 106, and the B prism 102 guides only the blue band light to the blue light imaging element 107. In addition, the R prism 103 guides only the red band light to the red light image sensor 108.

  In the manufacture of such an imaging apparatus, the B prism 102 and the R prism 103 are joined to the G prism 101 so that the optical path lengths to the blue light imaging element 107 and the red light imaging element 108 coincide. The Then, for each of the green light imaging element 106, the blue light imaging element 107, and the red light imaging element 108, position adjustments such as registration adjustment, tilt adjustment, and back focus adjustment are performed, and then each is fixed. In this case, the image sensor for green light 106, the image sensor for blue light 107, and the image sensor for red light 108 are held via the air layer with respect to the corresponding exit surface of the color separation prism.

  By the way, in such an imaging apparatus, conventionally, a trimming filter for each color is provided between each solid-state imaging device and the corresponding exit surface of the color separation prism. However, in recent years, only a blue trimming filter (blue trimming filter) has been used because of demands for cost reduction and the fact that cadmium is included in the green and red trimming filters. This is because the dichroic film has an angle dependency, and thus it is necessary to use either the blue or red trimming filter. As the blue trimming filter, for example, colored glass such as “B390” or a glass substrate coated with an organic substance is used.

  On the other hand, Patent Document 2 describes an imaging apparatus in which an emission surface of a color separation prism and a solid-state imaging device are joined without an air layer. In this imaging apparatus, first, the solid-state imaging device and the corresponding prism member are joined, and then the prism members are joined together to form a color separation prism. That is, in this imaging apparatus, the back focus adjustment for each solid-state imaging element is adjusted by the bonding position of the prism members.

JP 50-159618 A Japanese Patent No. 2811985

  In the image pickup apparatus as described above, from the viewpoint of achieving both reduction in mass production cost and quality assurance, the green light image pickup element, the blue light image pickup element, and the red light use light for the color separation prism are not complicated. It is important to maintain the mounting accuracy and reliability of the image sensor.

  On the other hand, solid-state imaging devices continue to be reduced in size and increased in pixel count due to advances in semiconductor technology. When the solid-state image sensor is miniaturized in this way, the structure for holding the solid-state image sensor is also miniaturized. Therefore, in the structure in which an air layer is interposed between the solid-state image sensor and the prism, the mounting accuracy is In addition, it is difficult to ensure reliability.

  In particular, with respect to a blue light imaging device, a blue trimming filter is provided between the color separation prism and the number of adhesion portions is increased, so that it is difficult to ensure mounting accuracy and reliability.

  On the other hand, in the imaging device in which the emission surface of the color separation prism and the solid-state imaging device are joined without an air layer, reliability is ensured for the joining of the color separation prism and the solid-state imaging device, There is a problem that tilt adjustment of the solid-state imaging device cannot be performed. Therefore, it is difficult for this imaging apparatus to improve the peripheral image quality.

  Since downsizing and increase in the number of pixels of the solid-state imaging device will continue in the future, it is necessary to adjust the tilt to ensure mounting accuracy, and it is desired to achieve both reliability and reliability.

  Therefore, the present invention is proposed in view of the above-described circumstances, and in an imaging device including a color separation prism and a solid-state imaging device, position adjustment including tilt adjustment can be performed on the solid-state imaging device, It is an object of the present invention to provide an imaging device and a method for manufacturing such an imaging device, in which the mounting accuracy of each solid-state imaging device is ensured and the reliability of mounting of the solid-state imaging device is also secured.

  In order to solve the above-described problems and achieve the above object, an imaging apparatus according to the present invention has any one of the following configurations.

[Configuration 1]
A color separation prism that separates incident light into red band light, green band light, and blue band light and emits light of each color band light from different exit surfaces, and receives red band light emitted from the color separation prism. A solid-state imaging device for red light, a solid-state imaging device for green light that receives green-band light emitted from a color separation prism, and a solid-state imaging device for blue light that receives blue-band light emitted from a color separation prism One of the solid-state imaging device for red light and the solid-state imaging device for blue light is joined to the corresponding exit surface of the color separation prism without an air layer, and the other two solid-state imaging devices Is characterized in that it is held via an air layer with respect to the corresponding exit surface.

[Configuration 2]
In the imaging apparatus having the configuration 1, a trimming filter is interposed between the solid-state imaging element bonded to the emission surface of the color separation prism without an air layer and the emission surface. It is a feature.

  The manufacturing method of an imaging device according to the present invention has any one of the following configurations.

[Configuration 3]
A step of separating the incident light into red band, green band, and blue band light and emitting the light of each color band from different exit surfaces by joining a plurality of prism members; A step of disposing a solid-state imaging device for red light that receives red band light emitted from the first emission surface so as to face the first emission surface; and a second emission surface of the color separation prism. A step of arranging a solid-state image sensor for green light that receives green band light emitted from the second emission surface, and an emission from the third emission surface facing the third emission surface of the color separation prism. A solid-state image sensor for blue light that receives the blue-band light that is received, and either one of the solid-state image sensor for red light and the solid-state image sensor for blue light has a corresponding emission surface of the color separation prism Against the air layer The other two solid-state image sensors are adjusted with reference to the solid-state image sensor that is joined to the output surface without the air layer in the state through the air layer with respect to the corresponding output surface. It is performed, and it fixes after that.

[Configuration 4]
In the manufacturing method of an imaging device having configuration 3, a trimming filter is interposed between a solid-state imaging device that is joined to the emission surface of the color separation prism without an air layer and the emission surface. It is what.

  In the imaging apparatus according to the present invention, by having the configuration 1, either one of the solid-state imaging device for red light and the solid-state imaging device for blue light has an air layer interposed between the corresponding emission surfaces of the color separation prism. Since the other two solid-state imaging devices are held via the air layer with respect to the corresponding emission surface, registration adjustment is ensured. The tilt adjustment and the back focus adjustment can be performed, and the mounting accuracy can be ensured.

  Further, in the imaging apparatus according to the present invention, by having the configuration 2, the solid-state imaging device in which the trimming filter is interposed between the emission surface of the color separation prism does not pass the air layer with respect to the emission surface. Therefore, the reliability of the joining can be ensured.

  In the manufacturing method of the imaging device according to the present invention, by having the configuration 3, either one of the solid-state imaging device for red light and the solid-state imaging device for blue light is placed in air with respect to the corresponding exit surface of the color separation prism. Since bonding is performed without a layer, the reliability of bonding to the color separation prism can be ensured, and the other two solid-state imaging devices can be registered in a state where an air layer is interposed with respect to the corresponding emission surface. Since fixing is performed after adjustment, tilt adjustment and back focus adjustment, the mounting accuracy can be ensured.

  Further, in the method of manufacturing an imaging device according to the present invention, the solid-state imaging device having the trimming filter interposed between the output surface of the color separation prism and the output surface of the color separation prism is interposed via the air layer. Therefore, the reliability of the joining can be ensured.

  That is, according to the present invention, in an imaging apparatus including a color separation prism and a solid-state imaging device, position adjustment including tilt adjustment can be performed on the solid-state imaging device, the mounting accuracy of each solid-state imaging device is ensured, and the solid-state imaging device is secured. It is possible to provide an imaging apparatus and a method for manufacturing such an imaging apparatus, which are configured to ensure the reliability of attachment of the imaging element.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[Configuration of imaging device]
FIG. 1 is a side view showing a configuration of an imaging apparatus according to the present invention.

  The imaging apparatus according to the present invention is an apparatus that separates and captures incident light into red band light, green band light, and blue band light corresponding to the three primary colors of light in video cameras and various camera lenses. As shown in FIG. 1, the imaging apparatus includes a color separation prism and a solid-state imaging device (CCD, MOS, etc.) 6 that receives red band light, green band light, and blue band light that are color-separated by the color separation prism. , 7 and 8.

  The color separation prism constituting the imaging apparatus includes a G prism 1 that is a prism member to which incident light A from an imaging lens (not shown) is incident, and a B prism 2 that is a prism member that is closely bonded to the G prism 1. The R prism 3 is a prism member that is tightly bonded to the B prism 2. A first dichroic film 4 that is a color separation film that reflects green band light is formed between the G prism 1 and the B prism 2, and blue band light is interposed between the B prism 2 and the R prism 3. A second dichroic film 5 that is a color separation film that reflects light is formed. The G prism 1 is provided with a light shielding groove for stopping ghost light.

  In this image pickup apparatus, the incident light A to the color separation prism reaches the first dichroic film 4 via the G prism 1, and only the green band light is reflected by the first dichroic film 4, and the other colors. The components are permeated to cause color separation. The green band light reflected by the first dichroic film 4 is totally reflected by the inner surface of the G prism 1, then exits from the exit surface of the G prism 1, and is received by the green light image sensor 6.

  The light transmitted through the first dichroic film 4 reaches the second dichroic film 5 through the B prism 2, and only the blue band light is reflected by this second dichroic film 5, and the components of other colors are transmitted. Color separation is performed. The blue band light reflected by the second dichroic film 5 is emitted from the emission surface of the B prism 2 and is received by the blue light imaging device 7. A blue trimming filter 2 a is tightly bonded to the emission surface of the B prism 2. That is, in the manufacture of this imaging apparatus, the blue light imaging element 7 is joined to the emission surface of the B prism 2 with the blue trimming filter 2a interposed therebetween without an air layer.

  As the blue trimming filter 2a, for example, colored glass such as “B390” or a glass substrate coated with an organic substance can be used.

  The light (red band light) that has passed through the second dichroic film 5 passes through the R prism 3, exits from the exit surface of the R prism 3, and is received by the red light imaging device 8.

  Thus, in this color of the image pickup device, the G prism 1 guides only the green band light to the green light image sensor 6, and the B prism 2 guides only the blue band light to the blue light image sensor 7. In addition, the R prism 3 guides only the red band light to the red light imaging device 8.

  In the manufacture of this imaging apparatus, the green light imaging element 6 and the red light imaging element 8 are held on the emission surface of the G prism 1 and the emission surface of the R prism 3 via an air layer. The green light image sensor 6 and the red light image sensor 8 are fixed after registration adjustment, tilt adjustment, and back focus adjustment with respect to the blue light image sensor 7.

  Here, when the refractive index of the glass material forming the B prism 2 and the blue trimming filter 2a is n, the B prism 2 has an exit surface of the G prism 1, an exit surface of the R prism 3, an image sensor 6 for green light, and The optical path in the prism and the blue trimming filter 2a is configured to be longer than the other prism members by n times the thickness of the air layer between the red light imaging element 8. When the thickness of the air layer is 0.3 mm and n is 1.5168, for example, the optical path in the B prism 2 and the blue trimming filter 2a is only 0.3 mm × 1.5168 = 0.455 mm. The optical path in the G prism 1 and the R prism 3 is longer.

[Method for Manufacturing Imaging Device]
FIG. 2 is a process diagram showing a method for manufacturing an imaging device according to the present invention.

  In order to manufacture the imaging device according to the present invention, first, a color separation prism is manufactured. In order to manufacture the color separation prism, as shown in FIG. 2, the G prism 1, the B prism 2, and the R prism 3 are respectively formed, and each dichroic film is formed on a predetermined optical surface of the prisms 1, 2, and 3. 4 and 5 are formed. Each of the prisms 1, 2, and 3 is created through each process of roughing (grinding, grooving, etc.) and finishing (lapping, polishing) of the glass material. The dichroic films 4 and 5 are formed by a film forming process such as vapor deposition.

  Next, as a prism assembling step, the B prism 2 is tightly joined to the G prism 1, and the R prism 3 is tightly joined to the B prism 2.

  Next, the blue light imaging element 7 is joined to the emission surface of the B prism 2 via the blue trimming filter 2a without an air layer. Then, the green light image pickup device 6 and the red light image pickup device 8 are opposed to the emission surfaces of the G prism 1 and the R prism 3, and the blue light image pickup device 7 is used as a reference with the air layer interposed therebetween. After adjusting the adjustment, tilt adjustment and back focus adjustment, it is fixed. The green light image sensor 6 and the red light image sensor 8 are fixed in a state called aerial bonding.

  Here, when the refractive index of the glass material forming the B prism 2 and the blue trimming filter 2a is n, the B prism 2 has an exit surface of the G prism 1, an exit surface of the R prism 3, an image sensor 6 for green light, and The optical path in the prism and in the blue trimming filter 2a is configured to be longer than the other prism members by n times the thickness of the air layer between the red light imaging element 8. If the thickness of the air layer is 0.3 mm and n is, for example, 1.5168, the optical path in the B prism 2 and the blue trimming filter 2a is 0.3 mm × 1.5168 = 0.455 mm. The optical path in the G prism 1 and the R prism 3 is made longer.

  In this method of manufacturing the imaging device, there is no gap between the exit surface of the B prism 2 and the blue trimming filter 2a and between the blue trimming filter 2a and the cover glass of the blue light imaging element 7 with an adhesive. It is glued. Therefore, reflection on the cover glass of the blue light imaging element 7 can be prevented, and high temperature reliability and temperature cycle reliability can be ensured.

  In this method of manufacturing an image pickup apparatus, relative back focus adjustment is performed with respect to the image sensor for green light 6 and the image sensor for red light 8 on the basis of the image sensor for blue light 7. This is to cancel the axial chromatic aberration of the imaging lens. When the imaging lens is a zoom lens (focal length variable lens), adjustment is performed so that axial chromatic aberration is canceled in a state where the focal length of the imaging lens is minimized (wide end).

  In this method of manufacturing an imaging apparatus, back focus adjustment and tilt adjustment cannot be performed for the blue light imaging element 7, but the back focus adjustment is absorbed by zoom adjustment of the imaging lens after mounting an imaging lens (not shown). Can do. Specifically, this can be done by searching for the focus position at the mounting position of the blue light image sensor 7 and storing this information in the memory as adjustment position information.

  Regarding the tilt adjustment, the contribution of the blue band light to the Y sensitivity is 11%, which is lower than the red band light and the green band light. Therefore, if the shape accuracy of the prism member is ensured, the adjustment is necessary. Absent. The Y sensitivity is expressed by the following equation.

[Y sensitivity] ≈ 0.29 [R sensitivity] + 0.59 [G sensitivity] + 0.11 [B sensitivity]
As can be seen from this equation, the solid-state image sensor to be joined to the color separation prism without an air layer may be the red light image sensor 8 instead of the blue light image sensor 7. In this case, the green light imaging element 6 and the blue light imaging element 7 are opposed to the emission surfaces of the G prism 1 and the B prism 2, and the red light imaging element 8 is used as a reference with the air layer interposed therebetween. As a result, the image is fixed through registration adjustment, tilt adjustment, and back focus adjustment. In this case, it is preferable not to use the blue trimming filter 2a, but to provide a red trimming filter between the emission surface of the R prism 3 and the red light imaging device 8.

[Second Embodiment]
In the above-described embodiment, the blue trimming filter 2a is interposed between the B prism 2 and the blue light imaging element 7. Instead of the blue trimming filter 2a, the emission surface of the B prism 2, or A blue trimming filter may be formed by printing or forming an organic film on the cover glass of the blue light imaging element 7.

  In this case, since there is no glass base material forming the blue trimming filter 2a, the exit surface of the B prism 2 and the cover glass of the blue light image sensor 7 can be adhered without any adhesive, and high temperature reliability, The temperature cycle reliability can be ensured more reliably.

  In this case, the B prism 2 has an exit surface of the G prism 1 and an exit surface of the R prism 3, an imaging element 6 for green light, and an object for red light, where n is the refractive index of the glass material forming the B prism 2. The optical path in the prism is configured to be longer than the other prism members by n times the thickness of the air layer between the image sensor 8 and the image sensor 8. When the thickness of the air layer is 0.3 mm, for example, if n is 1.5168, the optical path in the B prism 2 is 0.3 mm × 1.5168 = 0.455 mm, the G prism 1 and The light path is longer than the optical path in the R prism 3.

  Note that the trimming filter formed by printing or forming an organic film in this way is not limited to the exit surface where the solid-state image sensor is joined without an air layer, and the solid-state image sensor is opposed to the air layer via the air layer. It may be provided on the exit surface. That is, when the exit surface of the B prism 2 and the cover glass of the blue light imaging device 7 are closely bonded, a red trimming filter may be formed on the exit surface of the R prism 3. In the case where the surface and the cover glass of the red light imaging element 8 are closely bonded, a blue trimming filter may be formed on the exit surface of the B prism 2.

  In any case, the prism member having the exit surface to which the solid-state image sensor is joined without an air layer is n times the thickness of the air layer between the exit surface of the other prism member and the solid-state image sensor. Accordingly, the optical path in the prism is made longer than the other prism members.

It is a side view which shows the structure of the imaging device which concerns on this invention. It is process drawing which shows the manufacturing method of the imaging device which concerns on this invention. It is a side view which shows the structure of the conventional imaging device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 G prism 2 B prism 2a Blue trimming filter 3 R prism 4 1st dichroic film 5 2nd dichroic film 6 Green light image sensor 7 Blue light image sensor 8 Red light image sensor A Incident light

Claims (4)

A color separation prism that splits incident light into red band light, green band light, and blue band light, and emits each of these color band lights from different exit surfaces;
A solid-state image sensor for red light that receives red band light emitted from the color separation prism;
A solid-state image sensor for green light that receives green band light emitted from the color separation prism;
A solid-state image sensor for blue light that receives blue band light emitted from the color separation prism, and
Either one of the solid-state image pickup device for red light and the solid-state image pickup device for blue light is bonded to a corresponding emission surface of the color separation prism without an air layer,
The other two solid-state imaging devices are held via an air layer with respect to the corresponding emission surface. The trimming filter is interposed between the solid-state imaging device that is joined to the emission surface of the color separation prism without an air layer, and the emission surface. Imaging device. A step of splitting incident light into red band light, green band light, and blue band light and emitting each color band light from different emission surfaces by joining a plurality of prism members;
Disposing a solid-state imaging device for red light that receives the red band light emitted from the first emission surface so as to face the first emission surface of the color separation prism;
Disposing a solid-state image sensor for green light that receives the green band light emitted from the second emission surface, facing the second emission surface of the color separation prism;
Disposing a solid-state imaging device for blue light that receives blue band light emitted from the third emission surface, facing the third emission surface of the color separation prism, and
Either one of the solid-state image pickup device for red light and the solid-state image pickup device for blue light is joined to a corresponding emission surface of the color separation prism without an air layer,
The other two solid-state imaging devices perform position adjustment with reference to the solid-state imaging device joined to the emission surface without an air layer in a state via an air layer with respect to the corresponding emission surface, A method for manufacturing an imaging device, wherein the imaging device is fixed thereafter. The imaging apparatus according to claim 3, wherein a trimming filter is interposed between the solid-state imaging device that is joined to the emission surface of the color separation prism without an air layer, and the emission surface. Production method.

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